The present invention relates to systems and devices used to load containers. More particularly, the present invention relates to a robotic end effector used to load mail trays of different shapes and sizes into containers.
Millions of pieces of mail are deposited with the postal service every day. The deposited mail is sorted, generally by ZIP or other code, and shipped to the proper destination. Generally, the sorting process involves placing mail with the same or related codes into trays. The trays are then placed in containers for shipment. Some parts of this process have been automated, including the sorting of mail by ZIP code. However, the trays are often placed in the containers manually. With ever-increasing mail demands, faster, more efficient methods of and devices for loading containers with mail trays are needed.
The present invention provides an improved end effector for handling mail trays and tubs. The end effector includes first and second carriages, each having a pair of fingers depending therefrom. At least one of the carriages is movable toward the other carriage to grasp a tray between the respective pairs of fingers. The pairs of fingers counter-rotate to cause the support portions to engage and disengage the tray.
Each carriage has a body and first and second fingers. Each finger has a support portion and a journal portion having a longitudinal axis. The journal portion of each finger is supported by the body for rotation about the longitudinal axis. The support portion is angled with respect to the longitudinal axis. At least one actuator selectively causes the journal portions to counter-rotate with respect to each other. Because the fingers counter-rotate with respect to each other, the friction forces between each finger and the tray offset the friction forces between the other finger and the tray, such that the tray remains substantially in the desired stacking orientation.
In a preferred construction, the carriage includes first and second actuators, and the first and second actuators cause the first and second fingers, respectively, to selectively rotate. A pair of spaced-apart journal bearings supports the journal portion of each finger for rotation with respect to the body. A split clamp and actuator arm may be disposed between each pair of journal bearings to interconnect each finger with an associated actuator. The clamp includes a change-out mechanism to facilitate replacement of the fingers. Spacers may be provided to facilitate rotation of the fingers, clamps, and actuator arms with respect to the body.
Preferably, the end effector also includes a harness assembly for supply lines between the end effector and the rest of the robot. The harness reduces the likelihood of tangling and pinching the supply lines as the end effector moves with respect to the rest of the robot. The end effector also preferably includes a shelf lowering mechanism to manipulate shelves in the containers.
The present invention also provides a method for handling a tray. The method includes using an end effector having fingers to pick up and move the tray to a container, and counter-rotating the fingers to release the tray in the container.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.